On the Mechanism of Penetration of Liquids into Sintered Glass Powder Porous Bodies

Abstract

The rate equation of penetration of liquids into porous bodies was introduced on the assumption that the laminar flow is dominant over the entire duration of the penetration process:
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\ oindentand the solution of the above equation is given by;
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\ oindentwhere the equilibrium height of penetration (h_∞)=2γcosθ_∞⁄R_eρg, the tortuosity (T_e)=6(1−p)sinθ⁄π(π⁄3<θ<π⁄2) and the shape factor (C_e)=T_e⁄32, and the other symbol marks are; v, h and t: velosity, height at time t, p: porosity, R_e: effective radius of capillary tubes, η, γ and ρ: the viscosity, the surface tension and the density of liquid, θ_∞: the contact angle between solid and liquid, g: the gravitational acceleration, respectively.
From a comparison of the calculated values with the experimental ones, it has been confirmed that the above described solution is valid only for the penetration process into fully sintered porous bodies; i.e., for the case that the ratio of the diameter of necks between particles to that of powder particles is nearly equal to or not less than 0.5, where the turbulent flow is preferential at a very early stage of the penetration process. In the case of being less than this value it may be reasonable to suppose that the other resistant forces at the necks, due to local turbulence or adsorption, act on the motion of liquids in porous bodies.